From Japanese Patent No. 3226896, for example, there is known a front vehicle body structure for motor vehicles, where left and right front side frames 101 and 102 have their respective rear half portions that are bent relative to their front half portions toward each other, i.e. inwardly in a width direction of the vehicle, to prevent an engine-transmission unit from being accidentally displaced into a vehicle compartment.
The front vehicle body structure disclosed in the 3226896 patent will be described with reference to FIG. 13 hereof. The disclosed front vehicle body structure 100 includes left and right front side frames 101 and 102 disposed in a front section of the vehicle body. Of the left and right front side frames 101 and 102, portions 101a and 102a located rearwardly of the engine-transmission unit 103 are bent toward each other, i.e. inwardly in a width direction of the vehicle. The engine-transmission unit 103 is fixedly mounted, via mounting members 104 and 105, between respective front half portions 101b and 102b of the left and right front side frames 101 and 102.
As an impact load F is applied rearwardly to the front ends of the left and right front side frames 101 and 102, the front side frames 101 and 102 more or less compress or get squashed due to the applied load F, which could displace the engine-transmission unit 103 toward the rear of the vehicle body. However, such displacement of the engine-transmission unit 103 can be effectively prevented by the unit 103 abutting against the inwardly-bent rear portions 101a and 102a of the left and right front side frames 101 and 102. Thus, the engine-transmission unit 103 is prevented from abutting against a dashboard panel partitioning between the vehicle compartment and an engine room, so that a predetermined space in the vehicle compartment can be maintained or secured despite the applied impact load.
However, if the impact load F is relatively great, it may not be appropriately absorbed by only the compression or squash of the left and right front side frames 101 and 102. In such a case, the engine-transmission unit 103 would hit the inwardly-bent portions 101a and 102a without the impact load F being sufficiently absorbed. Therefore, there is a need to enhance more than necessary the rigidity of the engine-transmission unit 103 and left and right front side frames 101 and 102, in which regard a further improvement has to be made.